Need the largest negative number from a list in Python

Question

The assignment is:

Create an empty list called temperatures.
Allow the user to input a series of temperatures along with a sentinel value.
(do not use a number for a sentinel value) which will stop the user input.
Evaluate the temperature list to determine the largest and smallest temperature.
Print the largest temperature.
Print the smallest temperature.
Print a message that tells the user how many temperatures are in the list.

The issue I am having is that if my list contains [-11, -44, -77] my program prints -11 as the lowest temperature. But I need it to print -77.

My code:

# Create a list called temperatures to capture user input
temperatures_list = []

# Create a while loop to capture user input into the temperatures_list<br />
if __name__ == "__main__":<br />
    while True:
        enter_number = (input("Please enter a temperature (enter stop to end): "))
        if enter_number == "stop": break
        temperatures_list.append(enter_number)
    lowest_temp = min(temperatures_list)
    highest_temp = max(temperatures_list)
    total_temps = len(temperatures_list)

    # Print output of temperatures input by user
    print(f"The numbers you input are:", temperatures_list)
    print(f"The lowest temperature you input is: ", lowest_temp)
    print(f"The highest temperature you input is: ", highest_temp)
    print(f"There are a total of {total_temps} temperatures in your list")

You need to convert the inputs to integers. You're comparing strings. — Barmar, Jul 12 '21 at 16:49
Does this answer your question? [Why Python max() does not return maximum value?](https://stackoverflow.com/questions/63820220/why-python-max-does-not-return-maximum-value) Same problem but with max instead of min — Ryan Schaefer, Jul 12 '21 at 16:51
No, your list doesn't contain `[-11, -44, -77]`. See how to create a [mcve]. Challenge your assumptions. — Peter Wood, Jul 12 '21 at 16:53
Does this answer your question? [How can I read inputs as numbers?](https://stackoverflow.com/q/20449427/6045800) — Tomerikoo, Jul 12 '21 at 16:59
@barmar, if I use INT, then my sentinel (stop) will not work and the program errors out — Trottd, Jul 12 '21 at 17:02
@peterWood my list is populated by the user input. I was simply providing an example when stating [-11, -44, -77] — Trottd, Jul 12 '21 at 17:05

score 1 · Answer 1 · answered Jul 12 '21 at 16:51

1

Convert the input to int before adding it to temperatures_list:

while True:
    enter_number = (input("Please enter a temperature (enter stop to end): "))
    if enter_number == "stop": break
    temperatures_list.append(int(enter_number))

answered Jul 12 '21 at 16:51

PIG208

2,060
2
10
25

score 1 · Accepted Answer · answered Jul 12 '21 at 16:54

The problem you're having is that the numbers are in string format, so min() and max() aren't comparing the numerical values of the list values. This should do the trick:

# Create a list called temperatures to capture user input
temperatures_list = []

# Create a while loop to capture user input into the temperatures_list<br />
if __name__ == "__main__":<br />
    while True:
        enter_number = (input("Please enter a temperature (enter stop to end): "))
        if enter_number == "stop": break
        temperatures_list.append(int(enter_number))
    lowest_temp = min(temperatures_list)
    highest_temp = max(temperatures_list)
    total_temps = len(temperatures_list)

    # Print output of temperatures input by user
    print(f"The numbers you input are:", temperatures_list)
    print(f"The lowest temperature you input is: ", lowest_temp)
    print(f"The highest temperature you input is: ", highest_temp)
    print(f"There are a total of {total_temps} temperatures in your list")

As a side note, you could add in a try-except to catch cases where the user enters values that aren't a number, as this would cause your program to crash when converting the values to integer-type. For example:

# Create a list called temperatures to capture user input
temperatures_list = []

# Create a while loop to capture user input into the temperatures_list<br />
if __name__ == "__main__":<br />
    while True:
        enter_number = (input("Please enter a temperature (enter stop to end): "))
        if enter_number == "stop": break
        try:
            temperatures_list.append(int(enter_number))
        except ValueError:
            print('That wasn't a number! Try again)

    lowest_temp = min(temperatures_list)
    highest_temp = max(temperatures_list)
    total_temps = len(temperatures_list)

    # Print output of temperatures input by user
    print(f"The numbers you input are:", temperatures_list)
    print(f"The lowest temperature you input is: ", lowest_temp)
    print(f"The highest temperature you input is: ", highest_temp)
    print(f"There are a total of {total_temps} temperatures in your list")

float() would also work if you'd like to include numbers with decimals in.

score 0 · Answer 3 · answered Jul 12 '21 at 16:51

0

Create a function

def lowest_temp(temps):
    p = 0
    for i in temps:
        if i < i+1:
            p=i
    return p

answered Jul 12 '21 at 16:51

Aaron Cloud

315
4
15

Need the largest negative number from a list in Python

3 Answers3